diff -r c237499a7fba -r ee311681e591 mercurial/parsers.c
--- a/mercurial/parsers.c	Wed Dec 03 22:56:42 2014 +0900
+++ b/mercurial/parsers.c	Thu Dec 04 12:02:02 2014 -0500
@@ -1978,6 +1978,9 @@
 			PyErr_SetString(PyExc_ValueError, "rev out of range");
 		return -1;
 	}
+
+	if (nt_init(self) == -1)
+		return -1;
 	return nt_insert(self, node, (int)rev);
 }